1. Field of the Invention
The present invention relates to (2-arylpropyl)silanes represented by the formula (III) and a process for the preparation of the formula (III) by the Friedel-Crafts alkylation of substituted aromatic compounds represented by the formula (I) with allylchlorosilanes as represented by the formula (II) in the presence of Lewis acid catalysts such as aluminum chloride. ##STR2##
In the formulas (I) and (III), R and R' represent independently hydrogen, alkyl (C.sub.1 -C.sub.4), phenoxy, fluoro, chloro, bromo, mercapto or mercaptomethyl, and Ar represents phenyl ring, naphthalene ring or biphenyl ring. X.sup.1, X.sup.2 and X.sup.3 represent hydrogen or chloro group. In formula (III) according to the present invention specifically excludes the compounds of the general formula (III) in which X.sup.1, X.sup.2 and X.sup.3 are all chloro group, and R is hydrogen and R' is hydrogen, chloro or bromo, and X.sup.1 is hydrogen and X.sup.2 and X.sup.3 are all chloro, and R and R' are all hydrogen.
2. Description of the Prior Art
Hurd reported first the direct synthesis of allyldichlorosilane from allyl chloride and metallic silicon in 1945 (D. T. Hurd, J.Am. Chem. Soc., 67, 1813(1945)). When allyl chloride was reacted with a 9:1 Si--Cu alloy, a vigorous exothermic reaction occurred even at 250.degree. C. The obtained condensate contained trichlorosilane, tetrachlorosilane, allyldichlorosilane, diallyldichlorosilane and allyltrichlorosilane due to the decomposition of allyl chloride during the reaction. This reaction has never been used on a large scale in industry, because of the decomposition of allyl chloride and the easy polymerization of diallyldichlorosilane at high temperature above 130.degree. C.
Mironov and Zelinskii also reported that they obtained only 644 g of a mixture of allylchlorosilanes from the reaction of a 5:1 Si--Cu alloy with 2 kg of allyl chloride at 300.degree. C. The product mixture contained 356 g of allyldichlorosilane, 185 g of allyltrichlorosilane, and 103 g of diallydichlorosilane (V. M. Mironov and D. N. Zelinskii, Isvest. Akad. Nauk S.S.S.R., Otdel Khim. Nauk 383(1957). The production of allyldichlorosilane and allyltrichlorosilane indicates that allyl chloride decomposed under the reaction conditions and dehydrochlorination or dechlorination were accompanied. This is why the yield was under 30%, indicating that the process was not economically feasible. ##STR3##
The present inventors reported a preparation method of allylchlorosilanes by directly reacting silicon metal simultaneously with allyl chloride and hydrogen chloride in the presence of copper catalyst at a temperature from 220.degree. C. to 350.degree. C. Allyldichlorosilane was obtained as the major product indicating one mole of each of the allyl chloride and hydrogen chloride reacted with the same silicon atom. When sufficient hydrogen chloride was added, diallyldichlorosilane was not formed. This eliminated the polymerization problem involved in the direct synthesis (Korean Patent Application 92-10292 (92.6.1.3)). ##STR4##
Petrov and his co-workers reported that allyldichlorosilane can be disproportionated to allylchlorosilane and allyltrichlorosilane in the presence of pyridine catalyst (A. D. Petrov and V. M. Vdovin, Izv. Akad. Nauk SSSR, Ser. Khim., 1960, 519). ##STR5##
Nametkin and his co-workers reported that the Friedel-Crafts type addition of allylchlorosilanes to mono substituted benzenes to give 3-phenyl-1-silabutanes (N. S. Nametkin, V. M. Vdovin, E. S. Finkelshtein, V. D. Oppengeium and N. A. Chekalina, Izv. Akad. Nauk SSSR, Ser. Khim., 1966(11), 1998-2004). They reacted allyltrichlorosilane, allyldichlorosilane, allylmethyldichlorosilane or allyltrimethylsilane with benzene, chlorobenzene, bromobenzene or benzyltrichlorosilane in the presence of aluminum chloride to give (2-arylpropyl)silanes. The yield of 2-(phenyl)propyldichlorosilane from the reaction of allyldichlorosilane with benzene was 60%. ##STR6##